For the purpose of shortening the time required for product development, it is becoming increasingly important to perform estimation and confirmation of performance and functions, which are conventionally done by tests using samples, during the initial period of development.
A physical system such as a machine can be considered as an organism of functions comprised of many components. Individual components collaborate and function while converting and exchanging energy with each other in accordance with partial roles of their shares, and dynamically blend in concord to accomplish the purpose and mission of a machine as a whole in accordance with the required performance. For example, various kinds of performance such as travel performance of an automobile appear as integrated characteristics of individual units such as an engine, transmission device, and the like. Since these characteristics involves a plurality of different engineering fields, conventionally, different theoretical systems are combined and modeled by a unique method that meets the purpose of each particular simulation. However, it is not efficient to provide simulations against many problems and to maintain and manage them.
To solve this problem, a modeling technique which is common to different fields and can easily integrate them is required.
The present inventors have proposed a technique for expressing each component by identifying the energy flow using concepts called potential and float variables using a system equation in Japanese Patent Laid-Open No. 9-91334 and the like, thereby expressing a unit built by a plurality of components as a matrix.
Also, the present inventors has proposed examples of simulation by applying the above contents to automobile components in Japanese Patent Laid-Open Nos. 11-282897 and 11-282898.
Furthermore, the following papers have been disclosed:
(1) Hiroaki Yosimura & Takehiko Kawase, “Multibody dynamics and symbolic scheme”, The Japan Society of Mechanical Engineers 72nd general conference lecture meeting lecture papers, pp. 417-418, Mar. 29 to 31, 1995;
(2) Shizuo Kakuta & Shigeyoshi Hiramatsu, “Modeling of virtual prototype, (part I)”, The Japan Society of Mechanical Engineers 72nd general conference lecture meeting lecture papers, pp. 421-422, Mar. 29 to 31, 1995;
(3) Shizuo Kakuta & Shigeyoshi Hiramatsu, “Modeling of virtual prototype, (part II)”, The Japan Society of Mechanical Engineers 72nd general conference lecture meeting lecture papers, pp. 381-382, Mar. 29 to 31, 1995;
(4) Takehisa Koda & Kouichi Inoue, “Fundamentals of bond graph”, The Journal of the Japan Society of Investment and Management Vol. 9, No. 1, pp. 25-31, 1997;
(5) Shigeki Hiramatsu, Yasuhiro Harada, Hiroyuki Aarakawa, Ken Komori, & Shizuo Kakuta, “Modeling of power train by applying the virtual prototype concept”, The Society of Automotive Engineers of Japan lecture meeting preprints 1974, pp. 177-180, Oct. 21 to 23, 1997;(6) Shizuo Kakuta, Masao Nagamatsu, Kouichi Maruyama, & Sigeki Hiramatsu, “Hierarchical functional model for automobile development”, The Society of Automotive Engineers of Japan lecture meeting preprints 974, pp. 177-180, Oct. 21 to 23, 1997;(7) Masao Nagamatsu, Sizuo Kakuta, & Akio Nagamatsu, “A new approach on modeling for product development”, The Journal of the Japan Society of Mechanical Engineers (Series C) Vol. 64, No. 622, pp. 131-138, June 1998;(8) Akio Nagamatsu, Sizuo Kakuta, & Masao Nagamatsu, “A new approach on modeling for product development”, The Journal of the Japan Society of Mechanical Engineers (Series C) Vol. 64, No. 627, pp. 108-115, November 1998;(9) Sizuo Kakuta, Masao Nagamatsu, & Akio Nagamatsu, “A new approach on modeling for product development”, The Journal of the Japan Society of Mechanical Engineers (Series C) Vol. 65, No. 632, pp. 99-106, April 1999;(10) Yosiki Hiramatsu, Sizuo Kakuta, Masao Nagamatsu, & Akio Nagamatsu, “Modeling for functional expression of rotary apparatus”, The Journal of the Japan Society of Mechanical Engineers (Series C) Vol. 65, No. 638, pp. 44-51, October 1999; and(11) Akio Nagamatsu, Sizuo Kakuta, & Shigeki Hiramatsu, “Approach of modeling for aiding product development of automobile development”, The Society of Automotive Engineers of Japan 2000 spring meeting preprints, 2000.
However, individual contents, schemes, or their application examples have been referred, a technique for handling all physical systems from a component of a single function to a system such as an automobile together, resources and tools for implementing such technique have not been available yet.
As one of approaches of modeling used to develop such machine products and conditions required therefor, so-called expansion and integration of models are known.
One of the principal objectives of such approaches is to model from component models to a large-scale product model as in actual products and components, and to allow recombination and disassembly of component models on a model. For this purpose, models must be able to achieve structurization by means of expansion that combines models while allowing coexistence of independence and continuity of models in a given layer, and also hierarchization that forms a high-order model by integrating component models of a given level and converting them into an equivalent function.
In order to implement such modeling, it is important to systematize the expansion & integration scheme and hierarchization scheme used in product development using expansion, integration, hierarchization, inclusion relation, and the like using functional and mechanism models, so as to clarify a mutual relationship.
For functional and mechanism models whose mutual relationship is clarified by systematization, equivalent model conversion by combining models is required on a governing equation that simulates them. Also, equivalent model conversion must model-convert storage characteristics expressed by derivative state variables included in a model into an equivalent storage characteristic. Especially, in order to convert an integrated model into a low-order model, a group of storage characteristics left upon series or parallel connection after erasing rigidity, moment of inertia, and the like which are not required in an entity must be converted into an equivalent characteristic. With this integration, all input/output state variables that couple functional models are constrained, and all constraint conditions in a system are erased.
In these expansion and integration processes, it is especially important to handle nonlinear elements in terms of the arithmetic volume and precision. Since nonlinear elements are built in a functional model as some variable elements, i.e., become one of variables of the governing equation, nonlinear elements are involved in the process more intricately toward upper layers as a result of integration, thus increasing the arithmetic volume, while if nonlinear elements are simplified to reduce the arithmetic volume, the prevision suffers.